Originally Posted by RAPC

At the 72 hour window, you might get a reduced price without the extra fuel charges. (About $84 total if it works) As I said in my first post though, I have seen a couple of examples recently where full charges were still being applied in that window, which suggests they may have fixed their late upgrade issue around charging for fuel. Still worth a try though if you don't mind a gamble.

At the airport, the fixed amount will be an amount decided on the day. There isn't a set price that is always used. If there are only 2 seats in PE that they can upgrade to, vs 10 seats on a different day and a half empty economy cabin, the prices will be radically different.

I would say that $300 per person (or less) for an upgrade from Y to PE may be possible on a very quiet flight, but typically it will cost more on the day, if available at all. If you really want to travel in PE, then I would pay the extra $300 per person with your miles, as you won't likely get much cheaper unless the 72 hour window trick might work. If it doesn't, then you are relying on the airport and there being availability to start with. Even if there is, the upgrade cost may cost you more than $300 per person, especially if they are only offering cash upgrades, which is more likely at a US airport with only a couple of Virgin flights a day. You also get whatever is left of the seats as everyone else has checked in and had them allocated.